I entered the industry in my early 30s and remember getting a really helpful piece of advice from a meetup talk. Enthusiasm for learning and the technology is a counter for most of the ageism in interviews. It will stop people from assuming you're set in your ways, a curmudgeon, out of date, or anything on those lines.

The "culture fit" excuse is a tough one, though. That framing can be used to unknowingly discriminate in all kinds of ways.